1. Field of the Invention
The present invention relates to a digital multifunctional imaging apparatus (hereafter referred to simply as “digital multifunctional apparatus”) which has a printing function and a scanning function, and is capable of copying a document by itself without being connected to an apparatus having a host function such as a personal computer.
2. Description of the Related Art
A digital multifunctional apparatus has an image processing function of enlarging or reducing an image based on image data read by an image sensor (scanner unit) in order to adjust the image based on the image data to, for example, a size of a printing paper. When a host apparatus such as a personal computer is connected to the digital multifunctional apparatus, such image processing can be easily performed with using a CPU (Central Processing Unit) in the host apparatus. On the other hand, in the case of a digital multifunctional apparatus of so-called stand-alone type that can copy a document independently, three CPUs are used for scan control, print control and entire control of the digital multifunctional apparatus, respectively, while one DSP (Digital Signal Processor) is used for image processing, in order to perform the copy process without being connected to a host apparatus, or without starting the host apparatus.
Meanwhile, an image processing apparatus in a video printer is known for producing a hard copy of a television image (refer to, for example, Japanese Laid-open Patent Publication Hei 8-23440). Also known is an image processing apparatus for converting image data output from a facsimile so as to adjust the image data to the resolution of a printer (refer to, for example, Japanese Laid-open Patent Publication Hei 4-222067). It is also known to enlarge or reduce an image using a CPU installed in a printer apparatus (refer to, for example, Japanese Laid-open Patent Publication Hei 7-162675). Furthermore, an image magnification apparatus is known which reduces or enlarges an image by partially removing an image output. clock signal, or by exchanging an image output clock signal for an image input signal (refer to, for example, Japanese Laid-open Patent Publication 2000-125118 and Japanese Laid-open Patent Publication Hei 2-243060).
However, the above-mentioned conventional digital multifunctional apparatus is configured to process images through a firmware using the DSP, so that the processing speed depends on the operating frequencies of the CPUs and the DSP in the digital multifunctional apparatus, in which the DSP operates in synchronization with the CPUs. Thus, in order to complete the image processing and start printing operation in a short time, it is necessary to increase the frequencies of the operating clock of the CPUs and the DSP in the digital multifunctional apparatus. For example, the frequency of the operating clock of the three CPUs is required to be about 100 MHz, while the frequency of the operating clock of the DSP is required to be about 200 MHz. Accordingly, it is needed to use many such CPUs and DSP, which are expensive and thus remain an obstacle to cost reduction.
This problem cannot be solved by using the technology disclosed in either one of the first three patent publications described above. On the other hand, the image magnification apparatus disclosed in either one of the last two patent publications described above requires a complex circuit configuration to partially remove an image output clock signal, or to exchange an image output clock signal for an image input signal, thereby increasing the manufacturing cost.